168 The Alligator and Its Allies 



few cells are seen sloughing off as in Figure 40 ; possi- 

 bly the act of feeding keeps the superficial scaly 

 cells rubbed off smooth. 



In the extreme posterior region of the roof of the 

 mouth the epithelium consists of a greater number 

 of layers (though the number is very variable) 

 than in the region shown in Figure 40. In this 

 posterior region, as noted above, glands are found. 

 These glands have the same structure as those 

 described in connection with the posterior region of 

 the tongue. 



The (Esophagus. Sections of the oesophagus 

 were made from two regions, an anterior, half -inch 

 caudad to the pharnyx, and a posterior region, 

 half -inch cephalad to the opening of the oesophagus 

 into the stomach (Fig. 35). 



The general structure of the wall of the oesopha- 

 gus, as seen under a low magnification, will first 

 be described, after which the minute structure of 

 the epithelium, as seen under high magnification, 

 will be discussed. 



In the anterior region the usual layers of the 

 vertebrate enteron are present, except, possibly, 

 the muscularis mucosa. 



The epithelium, to be described later, is, together 

 with the submucosa, thrown into complicated 

 folds ; its closely arranged and darkly stained nuclei 

 cause it to stand out in strong contrast to the other 

 tissues of the section (Fig. 41, e). 



The submucosa, sm, is of considerable thickness. 



